The right-foot shoe was my control, and the left-foot shoe was my first test.
Step 1: Materials
Your scruffy shoes
A plastic scrubber (or steel wool) -A friend of mine recommended using a toothbrush, but I found that it couldn't scrub hard enough.
Step 2: Apply Toothpaste
Step 4: Rinse
If there is a little bit of yellow that won't come off, don't fret. That's the glue that's holding the rubber on. It seems to become more obvious when shoes are washed.
Step 5: Scrub the Top
These shoes had quite a bit of dirt and dust in them. If yours are old and dirty, this step will benefit them. If they're new and you want to preserve the colour, ignore this. It might make them look faded.
Step 6: Rinse All the Way Through
Squeeze out the water to dry faster.
Step 7: Bam!
The regular toothpaste works great, but I may try this again later on with a whitening toothpaste or a hardcore industrial-strength hand-cleaner.